Until the TCP/IP implementation was released with Berkeley 4.2 in 1983, Unix had had only the weakest networking support. Early experiments with Ethernet were unsatisfactory. An ugly but serviceable facility called UUCP (Unix to Unix Copy Program) had been developed at Bell Labs for distributing software over conventional telephone lines via modem. UUCP could forward Unix mail between widely separated machines, and (after Usenet was invented in 1981) supported Usenet, a distributed bulletin-board facility that allowed users to broadcast text messages to anywhere that had phone lines and Unix systems.

Still, the few Unix users aware of the bright lights of the ARPANET felt like they were stuck in a backwater. No FTP, no telnet, only the most restricted remote job execution, and painfully slow links. Before TCP/IP, the Internet and Unix cultures did not mix. Dennis Ritchie's vision of computers as a way to “encourage close communication” was one of collegial communities clustered around individual timesharing machines or in the same computing center; it didn't extend to the continent-wide distributed ‘network nation’ that ARPA users had started to form in the mid-1970s. Early ARPANETters, for their part, considered Unix a crude makeshift limping along on risibly weak hardware.

After TCP/IP, everything changed. The ARPANET and Unix cultures began to merge at the edges, a development that would eventually save both from destruction.